The present invention relates to the control of a water jet propelled vessel. Such waterjet propelled vessels are known and can range in size from small personal watercraft to boats of up to 75 feet in length, or vessels of even larger size.
A waterjet-powered vessel is moved through the water by accelerating a stream of water through a nozzle, thereby moving the vessel in reaction to the accelerated stream of water. The nozzle can be fixed to the rear of the vessel and aimed to produce lateral forces on the vessel which are used to steer the vessel. The waterjet is either engaged and pumping water or not engaged and not pumping water. Multiple waterjets/nozzles can also be used. The nozzle at the rear of the vessel is also usually equipped with a reversing bucket which, when activated, redirects some or all of the nozzle flow to produce a reversed component of thrust on the vessel. A waterjet thruster can also be positioned in or near the bow of the vessel with its axis essentially perpendicular to the vessel's bow-stern axis to produce lateral forces at the bow of the vessel. Combined, the rear nozzle, reversing bucket and bow thruster can be used to simultaneously maneuver the watercraft in any desired direction or heading.
The vessel can be equipped with a multi-axis joystick that allows the operator to simultaneously control the nozzle angle, reverse bucket position, and bow thrusters. Forward and aft movement of the joystick activates the reverse bucket. Sideways movement of the joystick activates the bow thruster, and nozzle angle is controlled by a twisting movement of the joystick.
U.S. Pat. No. 6,234,100 to Fadeley, dated May 22, 2001, discloses a Stick Control System For Waterjet Boats and U.S. Pat. No. 6,230,642 to McKenney, dated May 15, 2001 discloses an Autopilot Based Steering And Maneuvering System For Boats. U.S. Patent Application No. 2003/0054707 to Morvillo, dated Mar. 20, 2003, discloses an Integral Reversing And Trim Deflector And Control Mechanism and U.S. Patent Application No. 2003/0079668 to Morvillo, dated May 1, 2003 discloses a Method And Apparatus For Controlling A Waterjet Driven Marine Vessel. These two patents and two patent applications are incorporated by reference herein.
Despite the degree of control offered by these maneuvering and steering control systems, there remains a need for a control system that improves control algorithms to provide a more predictable control system that is more intuitive to operate.